Compilation warnings

Due to
```
Commit: 1a56a39b4a97452a5c7c2d8e9d39ab28ca33dff0 [1a56a39]
Commit Date: Friday, February 21, 2020 9:07:13 PM

Restructure section handling
```
a number of compilation warnings (Windows) appeared:
```
c:\projects\doxygen\src\section.h(51): warning C4099: 'SectionInfo': type name first seen using 'struct' now seen using 'class' [C:\projects\doxygen\build\src\_doxygen.vcxproj]
  c:\projects\doxygen\src\section.h(50): note: see declaration of 'SectionInfo'
```

1 files changed, 1 insertions, 1 deletions

diff --git a/src/definition.h b/src/definition.h
index db64094..016cbe8 100644
--- a/src/definition.h
+++ b/src/definition.h
@@ -38,7 +38,7 @@ class MemberDef;
 class GroupDef;
 class GroupList;
 struct ListItemInfo;
-struct SectionInfo;
+class SectionInfo;
 class Definition;
 class FTextStream;